by D. Cardace et al., Nov 12, 2020 in Front.Earth.Sci.
Editorial on the Research Topic
Deep Carbon Science
Our understanding of the slow, deep carbon cycle, key to Earth’s habitability is examined here. Because the carbon cycle links Earth’s reservoirs on nano- to mega-scales, we must integrate geological, physical, chemical, biological, and mathematical methods to understand objects and processes so small and yet so vast. Here, we profile current research in the physical chemistry of carbon in natural and model systems, processes ongoing in the deepest portions of planets, and observations of carbon utilization by the deep biosphere. The relationships between the carbon cycle and planetary habitability are undeniable, forming a conceptual anchor to all work in deep carbon science.
Carbon minerals respond to changing pressures, temperatures, and geochemical conditions. The geologic record preserves evidence of transitional periods at the submicroscopic to regional landscape scales, and demonstrates interplay between carbon-bearing phases and the biosphere. In a new review, Morrison et al. (2020) cast a retrospective look through deep time and call for emerging approaches to clarify the coevolution of the biosphere and geosphere.
Critical to transformations of Earth’s carbon inventory over time are indomitable tectonics – which influence Earth’s surface environment, weathering, metamorphism, magmatism, and volcanism. The slow, deep (endogenous) carbon cycle refines and re-distributes carbon within Earth. In fact, over the 200-million-year-long time scale, important tectonic controls on carbon cycling emerge (Wong et al., 2019). Wong et al. (2019) document the spatiotemporal evolution of fluxes inferred from plate tectonic reconstructions, and highlight CO2 fluxes from continental rift settings post-Pangea. The volcanic flux of CO2 has been successfully reconstructed by direct study of CO2 flux through lakes and adjacent soils (Hughes et al., 2019), an important and often overlooked CO2 valve linking lithosphere, atmosphere, and hydrosphere. From perspectives rooted deeper in the tectonic system, the important roles that serpentinites play in the carbon cycle are evaluated in two senses: 1) serpentinite as a carbon vector to the deep mantle (Merdith et al., 2019), and 2) serpentine mud volcanoes as sites of carbon mobilization through organic acid release (Eickenbusch et al., 2019), in a Mariana Trench case study.